St. Charles County OWTS rules start with jurisdiction

St. Charles County uses the term OWTS for onsite wastewater treatment systems, the systems many people still call septic. The county says Building and Code Enforcement regulates OWTS in unincorporated St. Charles County and in jurisdictions where the county contracts.

That makes jurisdiction the first check. A rural-feeling address may still be in a city, and a city or contract area may change which permit path applies. The county tells residents to use its Permit Lookup Tool to determine the project area’s jurisdiction.

For a buyer or landowner, the practical question is not only whether the system works today. Ask who regulates it, whether a permit is required for installation, repair, alteration, or replacement, and whether public sewer access changes the answer.